The present invention relates to methods for manufacturing phase insulators.
Insulators for separating different winding phases of dynamoelectric machines such as motors are generally well known in the prior art. For example, Stein U.S. Pat. No. 3,575,623 of Apr. 20, 1971; McNeal U.S. Pat. No. 4,100,005 of July 11, 1978; and Droll United Kingdom Pat. No. 1,461,126 of Jan. 13, 1977 all illustrate and describe what is referred to herein as phase insulation. Moreover, U.S. Pat. No. 4,216,571 which was filed June 22, 1978 in the name of Sammy L. Miller and Alan L. Kindig and which issued into U.S. Pat. No. 4,216,571 on Aug. 12, 1980 (entitled: "Methods and Apparatus For Inserting Winding End Turn Phase Insulation") relates to, among other things, utilization of phase insulation.
The above-referenced patents and application contain subject matter which is relevant to the invention claimed herein and the disclosures of all of such patents and the application are incorporated herein by reference in order to shorten the content of this specification.
As thoroughly treated in the above-referenced McNeal and Droll patents, methods utilized long prior to the present invention in the fabrication of phase insulation have been wasteful of material. One of the more common practices heretofore has involved the stamping of phase insulation pieces from a sheet or strip of insulating material. This process has resulted in the production of large volumes of scrap, with the amount of scrap being generally proportional to the length of the "connectors" which interconnect generally planar insulation pieces that ultimately are circumferentially disposed in a stator assembly between radially spaced, circumferentially extending end turn portions of two different phase windings.
Another problem is that when phase insulators are to be stamped or die cut from insulating stock, different dies must be provided in order to produce insulators that are to be used with motors having different stack heights. For example, one die would be provided which would produce phase insulators having connectors of slightly over two inches for use in motors having core lengths (also called stack heights) of two inches. It will be understood that motor manufacturers typically produce motors having stack heights of relatively wide ranges, and wherein one stack height will differ from another by increments as small as 1/8 to 1/4 of an inch. Thus, insulators produced from a die such that the connectors are two inches long would not be usable with a motor having a stack height of 21/4 inches. This, of course, necessitates having a die capable of producing phase insulators with connectors having a length slightly in excess of 21/4 inches. It thus should be understood that it would be desirable to provide new and improved methods and apparatus that could be utilized in the manufacture of phase insulation and new and improved forms of phase insulation such that the waste or scrap problem previously mentioned is diminished and which also would help in solving the problem associated with large inventories of phase insulation dies. Desirably, an optimum solution would also reduce the lost time associated with setting up many different dies in order to provide phase insulators of different dimensions and would also reduce the overall maintenance expense associated with having many different dies that primarily differ one from another by the length of the connectors that are produced from such dies. The above-referenced Droll patent and McNeal patent represent one approach that may be used to solve some of the problems just mentioned. However, even when following the approach represented by McNeal and by Droll, it would be desirable to still further reduce the amount of material utilized in producing individual phase insulators.
The above-referenced Miller et al application teaches one approach for automatically placing phase insulation in stator cores; and the above-referenced Droll patent teaches a very different approach for machine placing phase insulation in the slots of stator cores. While those approaches are desirable, I have determined that some problems may be encountered due to the inherent nature of the insulator pieces that have been available heretofore. More specifically, when insulation pieces manufactured as illustrated in the Droll patent are placed in automatic coil placing equipment, problems arise due to the fact that the connectors of phase insulation fabricated as described by Droll do not become properly positioned in stator slots. In the case of the approach described by Miller et al, difficulties may be encountered in positioning the connectors of phase insulation in the slots of the insulator placing tooling disclosed by Miller et al.
The invention disclosed herein not only contribute to a solution of the waste, die inventory, and die maintenance problems discussed hereinabove; but also somewhat surprisingly, alleviate the problems that would be encountered when machine placing fabricated insulators where filamentary type connectors are used to interconnect planar insulation pieces.
More specifically, insulators produced as described in the Droll patent are produced from planar insulation material and filamentary material which typically is supplied in coiled or rolled form. Such material tends to have a curvature or "set". This curvature appears to remain and still be present in the material even after phase insulators have been formed. However, curvature of the connectors in the phase insulation pieces is particularly troublesome when machines are used to automatically place such connectors in long straight slots--whether such slots be the slots of a stator core or the slots of insulator placing apparatus.
Accordingly, it would be desirable to provide new and improved phase insulators characterized by straight filamentary connectors. It would also be desirable to provide new and improved methods and apparatus for producing phase insulators whereby the die inventory, die maintenance, and scrap problem associated with the prior art approaches is at least diminished. It would be especially desirable to provide new and improved approaches whereby phase insulators could be fabricated utilizing a filamentary connector approach as known hereinbefore but wherein better material utilization is accomplished and wherein problems associated with curved connectors are avoided.
Accordingly, it is a general object of the present invention to provide new and improved methods for making phase insulators whereby the above and other desirable features may be provided.
More specifically, it is one object of the present invention to provide new and improved methods of making phase insulators so that scrap associated with the manufacture of stamped insulation is no longer directly proportional to the length of connectors used in the phase insulation.
It is another specific object of the present invention to provide new and improved methods for producing phase insulators whereby stamped phase insulators may be produced from a single die and yet which may be utilized in stators of widely varying stack heights.
It is still another object of the present invention to provide new and improved methods of making phase insulators, such that the amount of material required for the connectors is diminished.
Yet another object of the present invention is to provide new and improved methods which accomplish the last stated object even when the insulators are fabricated as taught by either of the above-referenced McNeal or Droll patents.
Yet another specific object of the present invention is to provide new and improved methods so that phase insulators may be easily machine inserted into straight slots even when filamentary material is utilized as the connector portion of the phase insulation.